Shark Teeth Facts: What's so special about a shark's tooth?

If you don't know much about shark-tooth collecting, then you may not know that these relics are more than just teeth -- they're fossils. Sharks have been living on Earth for about 400 million years. When a shark dies and its cartilage dissolves, the teeth fall to the bottom of the ocean and get covered with sandy sediment. This sediment prevents oxygen and destructive bacteria from reaching the tooth, and it fossilizes over the course of about 10,000 years. That's why most of the teeth that are found and collected aren't white, but gray, black or brown -- the color of the sediment. The tooth absorbs the minerals in the sediment and these minerals eventually replace the dentine and enamel that makes up the tooth. Voila, you have a fossil on your hands.

The megalodon compared to a typical great white

HSW 2008

Like all other fossils, shark's teeth can be valuable, so they're readily bought, sold and traded by enthusiasts and collectors. The most valuable of all is the tooth of the giant megalodon shark. This bad boy was a prehistoric beast that makes the modern great white look like your average goldfish. Great whites these days vary in size from 7 to 20 feet (2 to 6 meters). The prehistoric megalodon may have grown to a whopping 60 feet (18 meters).

The tooth of the megalodon ranges in size from 3.5 to 7 inches (89 to 177 mm) in length and can weigh more than a pound (.4 kg). Locating any megalodon tooth is a great find, and anything over 4 inches is rare and valuable. These teeth can go for as much as several thousand dollars each on the auction Web site eBay, depending on the size and the location where it was unearthed. The other factor that determines the value of the tooth is the shape that it's in. Even though teeth are fairly well ­preserved as fossils, they can be slightly eroded and contain chips and cracks from undersea rocks and coral.

So one reason people collect shark teeth is the shear monetary value. There are dozens of Internet sites devoted to the sale of these collectibles. Another reason is that on any given hunt, you may find a tooth from a giant, prehistoric predator that's 10 to 50 million years old. Most people would agree that digging up a 1-pound fossilized shark tooth as big as your hand is pretty cool. We'll give you some tips on the best way and best places to find these valuable fossils on the next page.